Electrical vibrator and method of making same



July 26, 1960 r. TOGNOLA 2,946,874

5 ELECTRICAL VIBRATOR AND msmoo OF MAKING SAME Filed NOV. 26, 1956 FIG-5 INVENTOR.

BY Em w Unite ELECTRICAL VIBRATOR AND METHOD OF MAKING SAME Tullio Tognola, Sidney, N.Y., assignor to Bendix Aviation Corporation, Sidney, N.Y., a corporation of Delaware Filed Nov. 26, 1956, Ser. No. 624,396

12 Claims. Cl. 200-90) This invention relates to electrical apparatus, and more particularly to an electrically actuated vibrator, which is useful, for example, as an interrupter for generating elec- States Patent C) simplified and rugged construction which lends itself admirably to the permanent sealing of the movable elements thereof.

Another object of the invention is to provide an improved electrically actuated vibrator having a novel armature suspension and novel stator and armature construction.

A further object is to provide, in a vibrator of the type indicated, stator and armature elements of such configuration that the magnetic efficiency of such parts and the responsiveness of the armature to flux variations in the stator are-markedly improved.

Yet another object is to provide an improved spark A discharge apparatus including as a component thereof the above indicated electrically actuated vibrator of the invention.

Still further objects are to provide a vibrator of the type indicated having an improved simplified frame structure.

- The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be understood, however, that the drawings are for the purpose of illustration only, and are not intended as a definition of the limits of the invention.

In the drawings, wherein like reference characters refer to like parts throughout the several views,

Fig. 1 is a view in projection of a vibrator device embodying the present invention;

Fig. 2 is a view in longitudinal vertical section through the device of Fig. 1, certain of the parts being shown in elevation;

Fig. 3 is an exploded enlarged fragmentary view in elevation of the stator and armature of the vibrator device;

Fig. 4 is a view in horizontal section through the vibrator of Figs. 1, 2 and 3, the section being taken generally along the line 4-4 of Fig. 2; and

Fig. 5 is a schematic wiring diagram illustrating the operating circuit of the illustrated vibrator, the vibrator being shown connected to a spark discharge device.

Fig. 6 is an enlarged fragmentary view in central vertical section through an alternative stator construction in accordance with the invention.

The embodiment of the vibrator of the invention illustrated in the accompanying drawings, by way of example, is in the form of a small compact unit 10 which is useful as an interrupter for generating electrical pulses to energize a spark discharge device such as shown in Fig. 5.

The spark discharge device may be employed to advanice tage, for example, to initiate combustion in a jet or turbine engine.

The construction of unit 10 will be apparent upon consideration of Figs. 2, 3 and 4. Device '10 has a frame made up of an elongated base plate 11 of magnetic metal to which are secured two parallel vertical cores 12, likewise of magnetic metal. The frame is completed by an elongated top frame member 14, made of magnetic metal, receiving the upper ends of cores 12. The upper ends of cores 12 are welded to frame member 14, which constitutes the stator of the vibrator.

A coil 16, wound on a spool 18, is disposed about each of cores 12, the winding of the two coils being so connected that the fluxes generated by the respective coils are additive. The path of flux flow is through a substantially, at least, closed flux path consisting of members 11, 12 and 14, as indicated by the small curved arrows in Fig. 5.

The upper plate 14, which forms the stator of the vibrator, is provided with a recess 17 having a frustoconical outer wall portion which converges downwardly or toward the coils. As most clearly shown in Fig. 3, recess 17 has a depth which is a large fraction of the thickness or vertical dimension of plate 14, there being a shallow circular cylindrical sidewall 28 at the bottom of recess 17 and coaxially therewith. Positioned in'such cylindrical portion of the recess is an insert 19 made of non-magnetic, and preferably poorly heat conducting, metal for a purpose to be discussed below. As shown in Fig. 3 a relatively thin portion 23 of plate 14, which remains after formation of the recess 17, is disposed beneath such recess. Thus the flux in its passage through plate 14 from one core 12 to the other, is highly concentrated'in the metal of the plate in the vicinity of recess 17. As a consequence, there is a pronounced leakage flux concentration through the air gap at recess 17.

In order further to increase such flux leakage through the air gap, there are provided two oppositely'disposed slots 20 through the thin walls of the recess and extending generally normal to the opposite elongated side edges of plate 14.

A movable armature 21, having a fuusto-conical outer wall generally complementary to the frusto-conical wall of recess 17, is disposed coaxially of such recess for reciprocation in directions axially inwardly and outwardly of the recess. Armature 21 is centrally secured to the lower broad surface of an elongated leaf spring 22, the ends of which rest upon similar post-like vertical extensions on the ends of plate 14. One end of the leaf spring is left free for sliding movement upon its support, the other end, shown in the left of Figs. 2 and 4, being secured A to its support by a pad member 25 overlying such end of the spring and secured to plate 14 by stud 24.

Centrally located on the upper broad face of spring 22, coaxiallywith armature 21, is a movable contact 26.

An upper contact 27 cooperating with contact 26 is secured to the lower inner end of stud 31 which is adjustably mounted in a bushing 33 sealed to an insulating bushing 30 on sheet metal housing 29. Bushing 30 is hermetically sealed to housing 29 in a conventional manner. Preferably the inner and outer surfaces of the bushing 30 are spray-coated with metal, such inner within it, is preferably hermetically sealed to plate 14 as by welding the lower edge of the housing to such plate. A connector having a strap 32 is afiixed to. the outer end of stud 31.

Leaf spring 22 is of such relaxedconfiguration, and

contact 27 is so adjusted, to thrust contact 26 at least slightly downwardly against the action of the spring when the coils 16 are not energized. When the vibrator is at rest, the lower inner end of armature 21 projects only partially into recess 17. When coils 16 are energized the flux concentration through the stator at recess 17 attracts armature 21 to cause it to move in a direction inwardly of the recess, thereby breaking the electrical circuit through the set of contacts 26, 27. In the illustrated embodiment of the vibrator of the invention, the contact set 26, 27 is interposed in an electrical circuit energizing coils 16 so that such contacts govern the operation of the vibrator. When the vibrator is thus employed and the parts thereof are connected as shown in Fig. 5, the frequency of vibration of armature 21 may be governed over an appreciable range by adjustment of the position of contact 27 by stud 31. Following such adjustment of stud 31, it is preferably welded at 52 to the outer end of bushing 33.

In Fig. there is schematically illustrated one manner in which the vibrator of the invention may be advantageously employed. The vibrator, which includes that portion of the circuit to the left of the vertical dotted line, is shown as having its coils 16 connected in parallel. Such coils are energized by a battery 34 having one terminal connected to ground and the other terminal connected to one end of coils 16 through leads, there shown as wire 36. It will be understood that current leads appearing as wires in Fig. 5 may be constituted by various parts, such as the leaf spring 22, stud 31, etc. of the vibrator shown. The other end of each of coils 16 is connected to ground, which may be the frame of the vibrator, through lead 39, movable contact 26, relatively fixed contact 27, and lead 32. Preferably, there is provided a condenser 40 connected in shunt with contacts 26, 27 to minimize sparking at the contacts. A manually operated switch 35 is interposed in lead 36 so that the vibrator may be started and stopped as desired. In the illustrated embodiment the vibrator is operative, that is, the armature 21 reciprocates as described when coils 16 are energized, independent of any electrical load connected to the vibrator.

In Fig. 5 a spark discharge device, generally designated 46, is connected to terminals 47 of the vibrator which in turn are connected to leads 26 and 39. Device 46 includes a voltage step-up transformer 41, the primary 42 of which is connected across terminals 47. The secondary 44 of transformer 41 has one end thereof connected to ground as shown, the other end of the secondary being connected to a spark gap 45.

When switch 35 is closed and the vibrator is in operation, current flows through primary 42 of transformer 41 when contacts 26 and 27 are in engagement, such current flow ceasing upon the opening of the contacts. Such rapid cyclic variations of current flow in primary 42 induces a high alternating voltage in secondary 44 of the transformer, such alternating voltage being high enough to discharge gap 45 at each peak of the voltage curve. Thus there is provided a rapid succession of spark discharges at the gap which continues as long as vibrator is in operation. Ordinarily, in the starting of jet and turbine engines, vibrator 10, and thus the spark discharge at gap 45, are stopped once the main engine flame has been started.

It will be noted top frame or stator member 14 is imperforate except for the openings therethrough sealed by the upper ends of cores 12 which are welded thereto. Thus when the housing 29 is sealed to member 14, the vibrator contacts 26, 27 are, in etfect, in a sealed container, so that the vibrator may safely be employed in an explosive gaseous atmosphere.

The above-mentioned insert 19, which is made of nonmagnetic metal, has poor heat conducting properties. Stainless steel has been suitable for insert 19. As a result, the heat applied to stator member 14 during the welding of housing 29 thereto is confined to the lower portion of member 14 in the vicinity of recess 17, thereby to prevent any marked deformation of the walls of recess 17, as by incipient fusion thereof.

An alternative construction of the stator of the vibrator, whereby the stator is improved in longitudinal rigidity, while preserving the hermetic sealing of contacts 26, 27 and safeguarding the recess in the stator against deformation during the welding of the housing 29 to the stator member is shown in Fig. 6. In such figure there is shown a fragment of a stator member 14' having a frusto-conical recess 17' therein. The bottom of the recess is closed by a relatively thin insert 50, which is preferably round in plan, which is positioned in a shallow counterbore 51 in the lower portion of member 14' coaxial of recess 17'. Insert 50, which is made of nonmagnetic metal such as bronze, is welded to member 14' so as to seal the bottom of recess 17. In this case, no side slots, such as slots 20 of the first embodiment, are employed. The flux fiow as the recess 17 is thus concentrated in the thin wall portions of member 14' bordering recess 17', since the bottom of the recess, formed by insert 50, is non-magnetic.

Insert strengthens member 14, and aids in shielding the sidewall of recess 17' from deleterious undue heating upon the welding of the housing 29 to stator member 14'.

Although only one embodiment of the vibrator of the invention, and one spark discharge apparatus incorporating such vibrator, are illustrated in the accompanying drawings and described in the foregoing specification, it is to be expressly understood that the invention is not limited thereto. For example, the specific construction of the resilient suspension of armature 21 may be varied rather widely. Also, in some cases, it may be desirable to charge a condenser by secondary 44 of transformer 41 through an interposed rectifier, the spark gap then employed discharging only after the condenser has been charged by a number of pulses from the secondary of the transformer. Further, whereas coils 16 is shown connected in parallel and the primary of the transformer is shown connected in parallel with the coils, the coils of the vibrator may be connected in series and in turn connected in series with the primary of transformer 41 and with the contacts 26 and 27. Various other changes may be made in the design and arrangement of parts illustrated as well as in the materials herein suggested without departing from the spirit and scope of the invention, as will now be apparent to those skilled in the art.

What is claimed is:

1. An electrically energized vibrator comprising a vibrator coil, a stator for said coil, said stator having a recess in a face thereof, an armature supported in alignment with the recess and projecting partially within the recess when the coil is deenergized, a first contact mounted on the armature and movable therewith and a second cooperating contact fixedly supported relative to said first contact, and means resiliently supporting the armature for movement in directions into and out of the recess when the coil is energized and deenergized, respectively.

2. A vibrator as defined in claim 1 wherein the recess has a width which is a large fraction of the width of the stator, whereby to increase the fiux density through the air gap in the stator at the recess.

3. A vibrator as defined in claim 2 wherein the recess has a depth which is a large fraction of the thickness of the stator.

4. A vibrator as defined in claim 3, comprising opposed slots through the sidewalls of the recess extending generally normal to the opposite side edges of the stator.

5. A vibrator as defined in claim 2 wherein the recess tapers inwardly and the armature is generally of the-same configuration as the recess.

6. A vibrator as defined in claim 5 wherein the stator is relatively narrow, and the recess has a width which is a large fraction of the width of the stator.

7. A vibrator as defined in claim 6 wherein the recess has a depth which is a large fraction of the thickness of the stator.

8. An electrically energized vibrator comprising a.

vibrator coil, a stator for said coil, said stator having a recess in a face thereof, an armature supported in alignment with the recess and projecting partially within the recess when the coil is deenergized, a leaf spring overlying and generally parallel to said face of the stator, means supporting the leaf spring, and means connecting the armature to said leaf spring.

9. An electrically energized vibrator as defined in claim 8 comprising a support for fixedly securing one end of the leaf spring and a support cooperating with the other end of said leaf spring, the armature being connected to the leaf spring generally centrally thereof.

10. A vibrator as defined in claim 8, comprising a set of cooperating contacts operated by said armature, one of said contacts being mounted on the armature and the other of said contacts being fixedly supported relative thereto.

11. Magnetic apparatus having a frame one member of which constitutes a stator, an armature-receiving 6V recess in the outer face of the stator extending inwardly a distance which is a large fraction of the thickness of the stator, and an insert plate of non-magnetic metal at the bottom of the recess and connected to the stator to form a sealed bottom of the recess.

12. Apparatus as defined in claim 11, comprising cooperating contacts one of which is mounted on the armature, and a housing which with the stator forms an enclosure for the contacts, the housing being welded to the stator.

References Cited in the file of this patent UNITED STATES PATENTS 1,578,998 Iakosky Mar. 30, 1926 1,770,090 Slisz July 8, 1930 1,932,164 Petit Oct. 24, 1933 2,000,868 Stowell May 7, 1935 2,009,892 Lecce July 30, 1935 2,036,295 Piifath Apr. 7, 1936 2,136,337 Green ct al Nov. 8, 1938 2,523,020 Hehenkamp et a1. Sept. 19, 1950 FOREIGN PATENTS Great Britain Iuly 18 1932 

